The fifth installment in Bethesda's Elder Scrolls franchise is set in the eponymous province of Skyrim, where the ancient threat of dragons, led by the sinister Alduin, is rising again to threaten all mortal races. Only the player, as the prophesied hero the Dovahkiin, can save the world from destruction.

Black Reach, some areas unavailable?

I have recently completed the Black Reach quest regarding the collection of 30 Crimson Nirnroots. When I was exploring for said plant life I found two areas which I can't figure out how to enter. I honestly cannot remember the names of the places, but one is a "marketplace" and the other location also seems (regarding the name of the door way) like you can enter and there should be something in this area, at least hallways and ancient Dwemer stuff. However, when I enter the space there is literally a wall in the way. But you can also here some sort of action happening nearby or behind the wall. Whether its an NPC or enemy I'm not so sure.

Has anyone had the same experience? Or am I missing something? Another quest line perhaps?